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By Henry FountainThe New York Times • Saturday February 16, 2013 7:23 AM

View SlideshowRequest to buy this photoFILE PHOTOTrees lie strewn across the Siberian countryside in 1953, 45 years after an asteroid exploded about 5 miles over Tunguska, Russia. The 1908 explosion is generally estimated to have been about 10 megatons; it leveled about 80 million trees for miles from the impact site.

The explosion of a small meteor over Siberia early yesterday was not the first time that that
part of the world has had a too-close encounter with a space rock. The region was the scene of what
is believed to be the largest space-related explosion in human history, 105 years ago.

The Tunguska Event, as it is known, occurred the morning of June 30, 1908, in a largely
uninhabited forest near the Podkamennaya Tunguska River in central Siberia. The site is about 1,200
miles northeast of Chelyabinsk, the Siberian city where some of the damage and injuries occurred
yesterday.

Scientists believe that an asteroid was the culprit in 1908, traveling in a northwesterly
direction and exploding at the altitude of a jetliner, about 5 miles. Recent calculations suggest
the object was relatively small, perhaps less than 100 feet in diameter. It’s been estimated that
the explosion was at least several hundred times more powerful than the atomic bomb that was
dropped on Hiroshima.

The airburst flattened tens of millions of trees over an area of about 800 square miles. Among
the few eyewitness accounts were reports of windows breaking and trees snapping 40 miles away.

The pattern of destruction on the ground was irregular, with fewer trees flattened in front of
the blast site and more to the sides. Experiments in the 1960s showed that this was due to the
interaction of two shock waves: one caused by the flight of the object, the other by the explosion
itself.

The event also produced a nighttime glow in the sky that persisted for several days and could be
seen across Europe and in Britain, about 3,000 miles from the site. Later experiments, including
some conducted aboard the space shuttle, suggest that this glow was due to clouds created as water
from the object entered the upper atmosphere. Those findings, in turn, point to the object being a
fragment of an icy comet rather than a me-

teor, but the issue is still the subject of much debate.

Nobody was injured by the meteor blast, nor by the Sikhote-Alin meteorite that fell in eastern
Siberia in 1947.